Crude oil and natural gas deposits generally are deep within the earth. To extract oil and gas, a well-bore is drilled into the earth and then crude oil is pumped up using submersible pumps, often in a series.
A well-bore is drilled from an oil-rig on the surface of earth using a rotating drilling bit. The drilling bit is driven using a continuous flow of compressed drilling fluid (also known as “drilling mud”) supplied through a conduit, known as a drill string.
When driven, the drilling bits cut through the earth and move deeper in, leaving a tubular well-bore. The inflowing compressed drilling fluid which drives the drill bits gets released at the bottom of the bore, and due to continuous pressurized drilling fluid inflow, released drilling fluid is pushed back to surface of the earth through free space available between the well-bore and the drill string.
On its way back to the surface of the earth, the released drilling fluid carries away with it:                loose dirt and rock from the bore (most of which is generated during cutting action of the drill bits);        gases (both trapped gases which were released while drilling the bore and gases which seeped into the bore from gaseous zones/formations surrounding the bore); and        water and other fluids (including both trapped water and fluids which were released while drilling the bore and others which seeped into the bore from regions/formations surrounding the bore).        
After reaching the surface of the earth, the used drilling fluid is collected, filtered and processed for reuse.
Apart from driving the drill bits, the drilling fluid also:                serves as a lubricant for the drilling bit;        removes the debris produced by the drill bits while cutting the bore and aids in further deepening it;        helps cool the drill bits under friction from cutting of the earth bed; and        provides hydrostatic pressure in the bore which reduces inflow, seeping in and unwanted escape of oil, gases and fluids from regions surrounding the bore.        
For a drilling fluid to be able to perform its desired functions, the correct composition and viscosity of drilling fluid must be maintained throughout the cycle. As drilling fluid is recycled, foreign material (such as rock debris and trapped gases) must be filtered out, and it must otherwise be processed to maintain the correct composition and viscosity. If trapped gases are not removed, the drilling fluid cannot provide the desired hydrostatic pressure. Additionally, as trapped gases may be flammable (such as methane or natural gas), there can be a risk of fire or explosion if they are not removed. Some trapped gases, including especially nitrogen and sulfur gas, can react with and corrode the drilling equipment, including the pumps. Trapped gases in the drilling fluid can also cause cavitation or even ‘gas-lock’ in the pumping equipment.
Over the years, various gas separators have been proposed for removal of trapped gases in the drilling fluid. Currently known gas-separators suffer from drawbacks including inefficiency in gas separation or otherwise; from lack of commercial viability; difficulty in installation in the limited available space of the bore; and inability to protect the pumping equipment. Hence, there's an acute need for a gas-separation equipment that overcomes the deficiencies of the prior art separators.